Rockwell Automation 1336T Wiring and Grounding Guide, (PWM) AC Drives - Manual (Page 26)

26 Rockwell Automation Publication DRIVES-IN001M-EN-P - March 2014
Chapter 2 Power Distribution
Delta/Delta with Grounded Leg,
or Four-wire Connected Secondary Delta
Delta/Delta with Grounded Leg or Four-wire Connected Secondary Delta is a
common configuration with no phase shift between input and output. The
grounded center tap provides a direct path for common mode current caused by
the drive output.
Three-phase Open Delta with Single-phase Center Tapped
Three-phase Open Delta with Single-phase Center Tapped is a configuration
providing a Three-phase delta transformer with one side tapped. This tap (the
neutral) is connected to earth. The configuration is called the antiphase
grounded (neutral) system.
The open delta transformer connection is limited to 58% of the 240V,
single-phase transformer rating. Closing the delta with a third single-phase,
240V transformer provides full rating for the two single-phase, 240V
transformers.
The phase leg opposite the midpoint has an elevated voltage when compared to
earth or neutral. The hottest high leg must be positively identified throughout
the electrical system. Make the hottest high leg the center leg in any switch, motor
control, three-phase panel board, and so on. The NEC requires orange color tape
to identify this leg.
or
Single-phase Loads
Single-phase Loads
Three-phase
Loads